Western Union / release of money transfer

I have sent $600 to Rwanda as a money transfer through Western Union. The agent on the receiving end will not release the funds to the receiver. Every time the person comes in to withdraw the funds, she is asked for yet one more piece of information. I called Western Union in the states and was told that they cannot do anything about it. The money was sent for medical reason and some one is waiting for an operation, Western Union doesn't care "it's not our problem" was their response. I am currently looking at taking legal action against them.